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Hydrodynamic Performance and Self–Stabilizing Mechanism of an Axially Symmetric Bow in Severe Sea Conditions
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Abstract
Deep bow immersion (bow–diving) during operation in severe cross seas poses significant survivability risks to surface vessels due to asymmetric waterplane variations that generate hazardous transverse hydrodynamic forces and heeling moments. This paper investigates the hydrodynamic performance of a novel axially symmetric bow design comprising a cylindrical main hull and a coaxial cylindrical bulbous bow. Numerical simulations combining Smoothed Particle Hydrodynamics for severe wave impact and RANS–VOF (ANSYS Fluent) for calm–water towing resistance were conducted. Grid convergence was established using the Grid Convergence Index , and the SPH formulation was independently validated against experimental benchmark data for dynamic water entry. Results under prescribed forced–immersion conditions demonstrate that the axially symmetric bow effectively suppresses asymmetric pressure distributions, reducing the maximum transverse force coefficient to (a 5.5 – fold reduction compared to conventional V–shaped bows under head seas). Parametric analysis reveals a strong passive restoring moment ( increasing the bulb length from to enhances by over 400% (from 0.20 to 0.85 at ), whereas doubling the bulb diameter from 0.25D to 0.5D yields a moderate 30% increase. While calm–water resistance increases by 21% at high speeds (22 knots) the resistance penalty is negligible) at operating speeds below 13 knots. These findings confirm a favorable localized geometry–driven self–stabilizing tendency, providing physical insights for the design of specialized offshore and arctic service vessels.
Keywords
Axially symmetric bow, bow–diving, hull form optimization, hydrodynamic stability, smoothed particle hydrodynamics
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References
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